3.1: Introduction

Overview

A topographic map is an extremely useful type of map that adds a third dimension (vertical) to an otherwise two-dimensional map defined by the north, south, east, and west compass directions. This third dimension on a topographic map is represented by contour lines, which are imaginary lines drawn on a map that represent an elevation above average sea level (a.s.l.) or mean sea level (m.s.l). A map with such elevation lines will provide the map reader with detailed information regarding the shape of the Earth’s surface. Knowledge of how to interpret a topographic map will allow a person to locate and identify features on the Earth’s surface such as hills, valleys, depressions, steep cliffs, and gentle slopes. In addition, the map reader will be able to identify areas that may be prone to geologic hazards such as landslides and flooding. Any person interested in purchasing property, landscaping, planning a hike or camping trip, or who needs to survey an area for construction of a road, dam, or building will want to first consult a topographic map.

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